The present invention is related to a baler for forming cylindrical bales and more particularly to a mechanism for tying such bales in the baler at the end of the bale formation.
Balers of this type are well known and comprise generally sets of bands, chains, or belts which, by their displacement, form, by winding inside a chamber provided in the body of the baler, a bale of generally cylindrical shape from harvested products, particularly forage or hay, collected on the ground during the advance of the baler through a field. Such bales are typically tied prior to discharge from the baler.
This operation, which is carried out with the aid of a tying material usually constituted by a length of twine, may be effected in known manner by means of a twine guide which is displaceable transversely of the direction of travel of the baler in front of the entrance for harvested products into the bale-forming chamber. The twine is withdrawn from a supply, such as a twine box, provided on the chassis or body of the baler. As a result of the transverse displacement of the twine guide, the twine, when it is pulled out by the rotation of the bale, forms helical turns around the bale and ensures the entire length of the bale is tied.
It is known (e.g., U.S. Pat. No. 3,913,473) to make the guide member for the twine in the form of an arm, especially in the form of a tubular arm, which is pivotably mounted on the baler in such a manner as to produce, under the action of suitable means, a transverse movement opposite the opening for the entry of the harvested products into the bale-forming chamber.
It is also known to have a twine guide which is displaced along a rectilinear guide arranged in front of the entrance of the harvested products into the bale-forming chamber. Means are then provided to bring about in a positive manner the displacement of the twine guide along the rectilinear guide. According to a known construction (German Patent Application No. 26 45 762), an electric motor is used to rotate a screw which is mounted in the twine guide by a guide member, similar to a carriage, with an element engaging the screw thread and enabling the twine guide to be displaced on the rectilinear guide. Electrical contacts are provided for enabling the appropriate displacements to be obtained. It will be understood nevertheless that an electric motor and electrical contacts, are scarcely compatible with the operational conditions of a baler and that harvested products can, for example, impede the operation of the electrical contacts and thus disturb the tying operation.
An object of the invention is to remedy the drawbacks of the existing constructions and to provide a device having a rectilinear guide in which the withdrawal of the twine by the bale automatically brings about the displacement of a twine guide along the a rectilinear guide.